Permissive joinder of parties is a procedural device allowing persons to join as plaintiffs or be joined as defendants in a single complaint. It is generally permissive, not mandatory, unlike the joinder of indispensable parties.

For permissive joinder of parties to be proper, the following conditions must be met:

• The right to relief must arise out of the same transaction or series of transactions connected with the same subject matter of the suit.
• There must be a question of law or fact common to all the plaintiffs or defendants. A question of law involves doubt as to what the law is on certain facts, while a question of fact involves doubt as to the truth or falsehood of alleged facts.
• Such joinder must not be prohibited by the rules on jurisdiction and venue.

When there are multiple parties involved, the joinder of causes of action is subject to these rules on the joinder of parties. This means the claims must arise from the same transaction or series of transactions and involve common questions of law or fact.

In cases of permissive joinder of parties, particularly when the claims are principally for the recovery of money, the total amount claimed across all joined causes of action determines jurisdiction (totality test).

The court can issue orders necessary to prevent any plaintiff or defendant from being embarrassed or put to expense in connection with proceedings where they have no interest.